Tracer bullet, self-sealing



1968 A. A. VENGHIATTIS 3,

TRACER BULLET, SELF-SEALING Filed May 20, 1966 Wmwwwwwuamwwwwuwamm ill/Ill]; Fl

INVENTOR.

A LEXls AVENGHIATTIS v 4 ZW ATTORNEY United States Patent 3,419,089 TRACER BULLET, SELF-SEALING Alexis A. Venghiattis, Weston, Conn., assignor to Dresser Industries, Inc., Dallas, Tex., a corporation of Delaware Filed May 20, 1966, Ser. No. 551,588 Claims. (Cl. 1754.57)

This invention relates to bullet well perforating and more particularly to a self-sealing projectile for use in perforating oil field well casing.

Bullet perforating is one of the common methods of perforating oil field well casing. In bullet well perforating, a bullet perforating gun is lowered into the well bore opposite the potential productive zone. The bullet perforating gun discharges a projectile which pierces the casing, the cement sheath, and after traveling a short distance, lodges in the formation. This procedure is normally used in the completion of a well, that is, the perforation caused by the projectile provides a path for the fluid from the formation to flow into the well bore.

It is desirable to be able to verify the depth of the perforations, and, in certain instances, the projectile has been filled with radioactive material which permits detection and, therefore, depth verification. However, in all cases, the projectile used in well perforating has been designed to fully penetrate the well casing and cement sheath surrounding such casing and extend into the formation. Thus, the use of such projectiles leaves a perforation and a flow path from the formation into the well bore.

In certain well completion techniques, it is sometimes desirable to inject a substance into the formation. However, in such instance, it may be undesirable to have a flow path from the well bore into the formation. Accordingly, the present invention is particularly directed to a projectile which is self-sealing, that is, while the front of the projectile will penetrate the casing and the cement sheath, the rear portion of the projectile is provided with means which will form a seal with the inner wall of the well casing. Such a projectile may be provided with a short life injectible radioactive material which will fiow into the formation. The injected radioactive material may be used for tracer operations as is well known in the art. The projectile may also be provided with acid or other compounds used in remedial well completion and work-over techniques. Such projectiles may also be provided with radioactive materials so that the depth of the projectile may be determined. It is also possible to provide such a projectile with flow means for use in sand control operations. In all cases unlike projectiles customarily used in bullet well perforating operations, the projectile of the invention is provided with means which establish a seal about the perforation.

The object of the present invention is to provide a projectile for bullet well perforating which is self-sealing.

It is another object to provide a bullet well perforating projectile which is so designed that the rear portion of the projectile will effect the seal with the inner wall of the well casing.

It is a further object to provide a self-sealing projectile for bullet well perforating which is provided with means to inject various substances into the formation.

It is a further object to provide a projectile for bullet Well perforating which is provided with sand control means.

The projectile of the present invention has a casing piercing nose portion, a seal-forming rear portion and an annular fiowable seal member, initially located just rear of the nose of the projectile. Upon impact, the forward motion of the seal member is arrested while the projectile continues forward momentarily until the sealforming rear portion of the projectile contacts the seal member at which time the forward movement of the projectile is arrested and a seal is formed around the perforation caused by the entry of the projectile into the casing. If desired, the projectile may be provided with a longitudinal bore which is sealed at its rear end. A series of radially-extending ports near the nose are in communication with the longitudinal bore. These ports are initially sealingly covered by the seal member. As mentioned, upon impact, the seal member moves away from the nose portion thereby exposing the radially-extending ports, permitting the fluid in the longitudinal bore to be injected. To aid in the injection, an inertial piston may be located in the rear of the longitudinal bore. Arresting of the projectile will cause the inertial piston to move forward injecting material in the longitudinal bore.

FIG. 1 is a cross-sectional view of a bullet well perforating gun having a projectile of the present invention positioned in a well bore.

FIG. 2 is an enlarged cross-sectional view of the projectile and barrel assembly shown in FIG. 1.

FIG. 3 is a cross-sectional view of a section of well casing illustrating the annular seal member being arrested by the inner wall of the well casing.

FIG. 4 is a view similar to FIG. 3 illustrating the formation of the seal by the self-sealing projectile.

FIG. 5 is a view similar to FIG. 4 showing a sand control filter in the projectile.

Reference will now be had to the drawings and particularly FIG. 1 which illustrates a novel projectile lit positioned in a bullet well perforating gun 12. The perforating gun 12 may be of the usual type used in bullet well perforating operations. One such gun is fully disclosed in Porter, US. Patent 2,953,971, dated Sept. 27, 1960, and as can be seen in FIG. 1 is generally comprised of a cartridge compartment 14 which contains a propellent charge 16, and a removable barrel assembly 18 in which the projectile 10 is initially positioned.

The propellent charge 16 may be ignited by an electrical contact pin 20 communicating with the rear of the gun or by any of other well known means in the art. Forward of the cartridge compartment 14 is the removable barrel assembly 18 having a central bore 22 in which is positioned the projectile 10. Ignition of the propellent charge 16 develops a sufiicient pressure to discharge the projectile 10 from the barrel 18 causing it to pierce the surrounding steel well casing 24, cement sheath 26, and just pierce the formation 28 as can be seen in FIG. 4.

The projectile 10 is formed of a casing-piercing nose portion 30, a seal-forming rear portion 32 and an annular seal member 34 which initially surrounds the nose portion 30. The casing-piercing nose portion 30 may be either ogive or conical or any other shape which has the desirable characteristics so that the projectile will penetrate the steel Well casing 24. Rearward of the nose portion 30 is a forward cylindrical portion 36. Extending rearward of the forward cylindrical portion 36 is an outwardly tapering portion 38 which extends toward the rear where it meets the large diameter seal-forming rear portion 32. The shoulder between the tapering portion 38 and the rear seal-forming portion 32 is a lip 40' which extends over the tapering portion 38.

Surrounding the forward end of the casing-piercing nose portion 30 is an annular seal member 34 formed of a malleable metal. The diameter of the inner Wall annular seal 34 is such that a press fit is established between it and the forward cylindrical portion 36. The diameter of the outer wall of the annular seal 34 is slightly less than the bore 22 of the barrel assembly 18 and the diameter of the seal-forming rear portion 32 of the projectile as seen in FIG. 2. Ignition of the propellent charge 16 will build up a pressure which will cause the projectile 10 together with the annular seal member 34 to move forward out of the barrel assembly 18. The casing-piercing nose portion of the projectile 10 will strike the well casing 24, and move through it; however, since the annular seal member is larger than the forward cylindrical portion 36, its forward motion will 'be arrested 'by the inner wall 42 of the casing 24, as can be seen in FIG. 3. Accordingly, the annular seal member 34 will remain stationary against the inner wall 42 of the steel well casing as the projectile 10 moves through the casing 24 and into the cement sheath 26. Shortly after the nose portion 30 of the projectile 10 enters the formation 28, the tapered portion 38 of the projectile 10 will contact the annular seal member 40 and cause the malleable material forming the annular seal member 40 to expand, then as the shoulder of the rear portion contacts it the material is formed between the projectile and the perforation forming a seal therewith, as can be seen in FIG. 4. Therefore, the projectile 10 of the present invention is self-sealing, i.e., there will be no communication between the inside of the well casing and the formation through the perforation.

As can be seen, the projectile 10 may be provided with a longitudinal bore extending from the rear end thereof forward to almost the nose portion 30. Just rearward of the nose portion 30 are several radially-extending ports 52 which are in communication with the longitudinal bore 50. The ports 52 are normally covered by the annular seal member 34. Inasmuch as the annular seal member 34 is press fitted unto the cylindrical portion 32, the radial ports 52 are sealed while the annular seal member remains in its initial position. Various substances such as radioactive markers, acid, and other materials may be placed in the longitudinal bore 50. In the rear of the fluid substance, there may be an inertial piston 54 and at the rear of the bore 50 is a plug 56 which forms a seal for the longitudinal bore 50. As before described, the annular seal member 34 is arrested by the inner wall 42 of the well casing 24 and, therefore, as the projectile 10 travels on through the casing 24, the radially-extending ports 52 are opened. When the forward motion of the projectile 10 is stopped by the rear sealing-forming portion 32 of the projectile 10 contacting the annular seal member 34, the inertial piston 54 will move forward discharging the fluid which is in the longitudinal bore 50 through the ports 52 as seen in FIG, 4. As previously mentioned, this fluid may be a radio-active tracer whereby any leakage behind the casing may be detected by means well known in the art. Also, other fluid materials may be put into the longitudinal bore 50 for treating the formation, as is well known in the art.

In certain formations, particularly unconsolidated sand, there is a tendency for the sand in the formation to flow through the perforation and sand up the well. If desired, the longitudinal bore 50 of the projectile 10 may be provided with a suitable filter 58, as seen in FIG. 5. In such case, communication with the formation would be through the radially-extending ports 52, filter '58, and a passage 60 in the plug 62 at the rear of the bore 50.

As can be seen from the foregoing, the projectile 10 Cir is provided with means which form a seal between the projectile and its perforation and is, therefore, self-sealing. The projectile is also so designed that it may be utilized to deliver various materials into the formation without resulting in establishing communication between the formation and the inside of the well bore.

1 claim:

1. A projectile for use in a bullet well perforating apparatus for firing a projectile inside a well casing, said projectile comprising:

a projectile formed of a well-casing-piercing nose portion designed to penetrate the well casing,

a forward cylindrical portion extending rearward of the nose portion, a rear cylindrical seal-forming portion of a greater diameter than the forward cylindrical portion, and

an annular malleable seal member surrounding the forward end of the forward cylindrical portion whereby upon the annular malleable seal member contacting the inner wall of the well casing, it remains stationary against the inner wall and when the rear end forming portion of the projectile contacts the seal member, the malleable material flows into the perforation forming a seal between the projectile and the perforation.

2. The projectile specified in claim 1 characterized in that there is an outwardly tapering portion between the cylindrical portion and seal-forming rear portion which expands the malleable material of the seal member as the projectile progresses through the casing.

3. The projectile specified in claim 2 is characterized in that it is provided with a longitudinal passage extending from the rear end to a point adjacent the nose portion and is provided with a plurality of radial ports providing communication between the longitudinal bore and periphery of the projectile, the ports being sealed by the annular seal member.

4. The projectile specified in claim 3 is characterized in that the rear end of the bore is sealed and an inertial piston is positioned in the bore to aid in the discharge of material in the bore.

5. The projectile specified in claim 3 is characterized in that a filter is positioned in the bore and there is a passage in the rear of the bore to provide communication from the ports through the bore to the inside of the well casing.

References Cited UNITED STATES PATENTS 2,355,513 8/1944 Cox 1754.57 X 2,468,729 5/1949 Black l6655.2 X 2,526,695 10/1950 Schlumberger 16655.1 2,544,601 3/1951 Kinley 16655.1 2,559,687 7/1951 Thomas 175-457 2,799,474 7/ 1957 Schneersohn 166100 X 2,884,836 5/1959 Allen 175-35 2,903,072 8/ 1959 Mennecier 166-400 DAVID H. BROWN, Primary Examiner.

US. Cl. X.R. 

1. A PROJECTILE FOR USE IN A BULLET WELL PERFORATING APPARATUS FOR FIRING A PROJECTILE INSIDE A WELL CASING, SAID PROJECTILE COMPRISING: A PROJECTILE FORMED OF A WELL-CASING-PIERCING NOSE PORTION DESIGNED TO PENETRATE THE WELL CASING, A FORWARD CYLINDRICAL PORTION EXTENDING REARWARD OF THE NOSE PORTION, A REAR CYLINDRICAL SEAL-FORMING PORTION OF A GREATER DIAMETER THAN THE FORWARD CYLINDRICAL PORTION, AND AN ANNULAR MALLEABLE SEAL MEMBER SURROUNDING THE FORWARD END OF THE FORWARD CYLINDRICAL PORTION WHEREBY UPON THE ANNULAR MALLEABLE SEAL MEMBER CONTACTING THE INNER WALL OF THE WELL CASING, IT REMAINS STATIONARY AGAINST THE INNER WALL AND WHEN THE REAR END FORMING PORTION OF THE PROJECTILE CONTACTS THE SEAL MEMBER, THE MALLEABLE MATERIAL FLOWS INTO THE PERFORATION FORMING A SEAL BETWEEN THE PROJECTILE AND THE PERFORATION. 